[Opium and opioids: a brief history.].

BACKGROUND AND OBJECTIVES In addition to their major influence on human behavior, opium and opioids have been used for a long time as sedative and analgesic drugs. As from the 19th century, with the isolation of opium alkaloids and easy parenteral administration of these substances, there has been increased interest in the judicious medical use of opioids and in the analysis of social consequences of their abuse, which has justified a historical review of opium and opioids. CONTENTS Further understanding of opium, natural product extracted from Papaver somniferum, and of opioids, natural opium-extracted semi-synthetic and synthetic substances, as well as major references to these substances since ancient times are evaluated. Breakthroughs after Setürner's studies, which have resulted in morphine isolation, are emphasized. Reference is made to other authors' investigations in the search for synthetic substances with advantages over natural products. The importance the discovery of opioid receptors and their endogenous binders is highlighted. CONCLUSIONS In the dawning of the third millennium, regardless of studies with analgesic drugs of different pharmacological groups, opioids are still the most potent analgesics, although their efficacy has been questioned for some types of pain. Current Clinical Pharmacology knowledge allows for the selection of the opioid based on patient's disease and conditions, in the search for the best cost-benefit ratio.